What is redundant encoding?

• A. When a protected attribute is correlated with other features, allowing the model to indirectly use the protected attribute
• B. Directly including the protected attribute as a feature
• C. When there is no correlation between protected attribute and features
• D. When the model ignores protected attributes

Answer: (A)

Redundant encoding means the protected attribute isn’t used directly, but signals about it leak into the model through features that are correlated with it. Because those features carry information about the protected attribute, the model can infer and use that information anyway, reintroducing bias even if you didn’t feed the protected attribute itself. That’s why describing a protected attribute being correlated with other features, allowing indirect use, is the correct idea. If there’s no correlation, or if the attribute is simply ignored or included directly, you don’t get this indirect leakage.